Second, I seem to recall there being a difference in frame size for DSLRs and it effecting compatibility of the lenses, but wasn't paying much attention and don't recall what the issue was. Maybe something about less than full frame sensors? Figment of my imagination? Something to do with the "Lens Focal Length Conversion Factor", whatever that is?

The sensor itself is physically smaller than a 35mm film plane. The Rebel XT, for instance, has a 22.2 mm × 14.8mm sensor. Some people refer to it as a magnification factor, but really, it's more of a crop factor.

If you have the cash and want to spend money on CF cards, then go for the 40D...

It's not like memory costs much these days. I remember in second year of college (2003?) I bought a San Disk Extreme 256MB CF card for something like $125. Just a few months ago I bought an Extreme III 8GB for something like $140.

In terms of what is superior between CF and SD... it's generally going to be CF, but for most users the difference is going to be negligible. With the speeds and storage capacity available with current high end SD cards it's already more than enough for the average shooter and the price is comparable to equivalent CF cards.

The Canon EOS-1Ds Mark III is an engineering tour de force which, true to the EOS-1 legacy, redefines the state of the art in no uncertain terms. An entirely new 21.1-megapixel full-frame Canon CMOS sensor delivers astounding image quality and creates new photographic possibilities. Dual "DIGIC III" Image Processors work in tandem to speed up data handling and camera operation, while further refining imaging performance. Tough, high-durability body and shutter designs, combined with the unique EOS Integrated Cleaning System, set new standards for professional dependability. Cutting-edge features-such as a large 3.0-inch LCD monitor with Live View Function, and a fast, precise 45-point AF system-make the EOS-1Ds Mark III powerful and versatile. And, of course, the EOS-1Ds Mark III is part of the unparalleled EOS System, which, with more than 50 EF lenses, 15 interchangeable focusing screens, and extensive wireless remote control and lighting accessories, is the most advanced and powerful digital photography system in the world.

It's kinda a mag-factor as well... on my 20D my 24-105mm lens is effectively a 38-168mm lens, due to the 1.6 crop factor. IOW, for the area of the image which is captured on the sensor, you'd need to blow it up 1.6X to get the same "negative" size as a standard 35mm negative.

You probably would never notice a difference in image quality between an image shot digitally at 100ISO and a 35mm negative shot at 100ISO, though you'd need to purchase a high-dollar scanner to get that negative into photoshop. Photoshop, IME, is where the real work is done. Too bad I haven't spent the time to develop those skills yet, but a good PS tech can do more with your image than the best darkroom tech ever could... PROVIDED HE HAS THE PIXELS TO WORK WITH!

Don't forget that once you start placing images in a commercial context, what the designer places emphasis on is often not just a 'pretty image' but one that meets a set of criteria specific to the final application.

$10???? 8GB?????? Guess its been a while since I bought SD cards....
-a.

Sorry, was skipping around between posts... I didn't realize they were making 8gig cards and thought my 2gig ones were fairly new.

-a.

Digital is available in full frame formats for "Professionals" the problem is, they're VERY expensive for the body alone, start factoring in glass and you're lookin at 10+K to get the full deal setup if you're starting from scratch.

stymingersfink, You can get a full frame canon 5d for around 1600 or so now (new with rebates), or a little bit less used. That is full frame. You can also get a used 1ds Mark II for around $3500, and the original 1DS for the 1500 range.

And, as for the crop factors, as was mentioned, it isn't a magnifying effect, so much as a limiting what you can see effect. Can be nice for telephoto, but sucks for wide angles.

For the OP, if you are just looking to get into dslr mostly for fun, then I think an xti, xsi, or used 30d would be a great place to start. Or, a 5d as well, if you don't mind spending a little bit extra. One thing to note about mp, is that the file sizes go up, big time! So, from 8 to 12 might make a big deal on hard drive space, card space, etc.

http://www.dpreview.com/reviews/CanonEOS450D/

check that link out, it's an extremely through review of the newest 12MP Canon Rebel. look around on the rest of the website - it's probably the most comprehensive review site for digital cameras out there. I myself have a 350D (Rebel XT, 8MP) that I use with a 18-200mm f/3.5 Sigma lens and I love it. Obviously two generations later they have added nice little bells & whistles. For work I just purchased a Canon 40D and a Canon 17-55mm f/2.8 lens which is about $1200 alone.

Anway a 350D, 400D or 450D will all serve you quite well - what lens you will be using, though, is probably even more important than the choosing between those three cameras. I went for range (18-200) at the expense of speed (only f/3.5) and that works great for me when I do climbing shots outside and don't have to f*** with changing lenses. The kit lens that comes with most DSLRs is complete crap. Buy the body only and then get a decent lens that you think will suit your purpose.

-bds

Well first of all, I like my Sigma but it's not an amazing lens by any means. This may offend you, at the least it's going to sound very snooty and elitist, but if you can't tell the difference between a kit lens and, for example, a Canon 17-55 f/2.8 IS USM you are likely vision impaired. That, or you just haven't taken enough pictures to see how each lens performs in various duties. I've never talked to a photographer who didn't say to throw the kit lens in the trash.

and then there are also things like chromatic aberration, which good lenses correct for and cheap kit lenses don't. there are many differences between good and cheap lenses that go beyond speed and as you mentioned sharpness. and IS (image stabilization) is soooo worth it.

Don't forget to buy a UV filter to protect the sensor !